/* 头部开始 */
header {
    border-bottom: 2px solid rgb(241, 241, 241);
}
.heart {
    width: 1200px;
    margin: 0 auto;
    overflow: hidden;
}
.logo {
    position: relative;
    float: left;
    height: 100px;
}
.logo .logoInner {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    z-index: -1;
}
nav {
    display: flex;
    justify-content: space-around;
}
nav li {
    box-sizing: border-box;
    height: 100px;
    line-height: 100px;
    font-size: 30px;
    color: #737373;
}
nav li:hover {
    border-bottom: 4px solid #ffd155;
    color: #0f9cf5;
}
/* 头部结束 */